.1 is down so I need it to direct to .2 I set up the DNS as follows as far as I can see then this is how I do it. It tries the mani MX 0 and fails so looks for second highest record MX 10 so it now knows the ip adress of the mail server in question - however as I need it to go to pop3 port on server .2 will it follow the same rule - ie first pop3 record is fail find another one and try?

pop3 IN A 125.0.0.1
smtp IN A 125.0.0.1
IN MX 0 125.00.0.1
IN MX 10 125.0.0.2
pop3 IN A 125.0.0.2
smtp IN A 125.0.0.2